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Home Energy · Flagship calculator

Home Energy Audit

Add up every appliance in your home to see annual kWh, running cost, CO₂ and share of the bill. Starts from a realistic mid-EU household — edit wattage and hours to match yours, add missing items, and let the audit surface your biggest quick wins.

Total annual use

6,156 kWh

16.9 kWh/day average.

Annual cost

€1,847

≈ €154/month.

Annual CO₂

1.8 t

1,847 kg at 0.3 kg/kWh.

Standby loss

350 kWh

= €105/year always-on.

Where your kWh go

Hot water36%Cooling8%Cooking16%Appliances23%Electronics9%Lighting2%Standby6%

Your appliances

ApplianceCategoryWattsh/daydays/yrkWh/yrCostCO₂ kgShare
438€131.41317.1%
292€87.6884.7%
313€93.75945.1%
525€157.51588.5%
47€14.17140.8%
420€1261266.8%
160€48482.6%
135€40.5412.2%
120€36.14362%
2,190€65765735.6%
146€43.8442.4%
175€52.56532.8%
250€75754.1%
108€32.4321.8%
105€31.54321.7%
175€52.56532.8%
70€21.02211.1%
486€145.81467.9%
Total6,156€1,8471,847100%

Your top 3 consumers

  1. 1

    Electric hot water tank

    2,190 kWh · €657 · 657 kg CO₂ · 36% of bill

  2. 2

    Induction hob

    525 kWh · €158 · 158 kg CO₂ · 9% of bill

  3. 3

    Air conditioner (summer)

    486 kWh · €146 · 146 kg CO₂ · 8% of bill

Quick-win recommendations

  • •Standby is costing you €105/year. A €30 smart plug on your TV/console cluster pays back in months.
  • •Your biggest single line is Electric hot water tank at 2,190 kWh. Cutting it by 20% saves €131/year.
  • •Dropping wash cycles from 60 °C to 40 °C cuts washing energy ~60%. See the smart-home savings guide.
  • •If you heat electrically, a heat pump typically cuts heating energy 3–4×. Try the heat pump savings calculator.
  • •Covering 100% of your usage with a 4 kWp rooftop PV system? See the solar payback calculator.

How the math works

Every row is one identical calculation. Watts × hours × days ÷ 1000 gives annual kWh; kWh × tariff gives cost; kWh × grid CO₂ intensity gives emissions:

Annual kWh = watts × hours/day × days/year ÷ 1000

Annual cost = kWh × tariff

Annual CO₂ = kWh × grid intensity

Share of bill = appliance kWh ÷ total kWh

Duty-cycled appliances (fridges, freezers, air conditioners) do not run at nameplate power the whole time they are plugged in — their compressor cycles on and off. Use effective compressor-on hours, typically 6–10 h/day for a modern fridge, not 24. The defaults in this audit already do that.

Standby losses are the row items marked always-on. Individually tiny (5–25 W), collectively they run 8,760 hours a year and typically add up to €50–€250 on a European bill. The audit calls this out separately so it is impossible to ignore.

Bill accuracy depends on how honest your wattage and hours are. If a line surprises you, buy a €15 plug-in wattmeter and measure the device for a week — you will get within ±5% of reality.

Frequently asked questions

How is annual energy use calculated per appliance?
Annual kWh = watts × hours per day × days per year ÷ 1000. For always-on devices (routers, standby loads) set hours to 24 and days to 365. For duty-cycled appliances like fridges, use effective compressor-on hours (typically 6–10 h/day for a modern fridge) rather than the 24 hours the plug is powered.
Why is my estimate different from my actual bill?
Three reasons. First, nameplate wattage is peak draw — many appliances use less on average. Second, we do not automatically include space heating (add it as a custom line if you heat electrically). Third, standing charges and taxes on your bill are not per-kWh. Compare only the energy portion. Real-world variance of ±15% is expected without a metered plug reading.
How do I audit space heating with this tool?
Add a custom appliance called "Heat pump" or "Electric heating" and enter its effective average power for your climate. For a 10 kW heat pump running an average of 8 hours per day across a 200-day heating season, use 10,000 W × 8 h × 200 days = 16,000 kWh/year. Cross-check with the heat pump SCOP guide for realistic seasonal power.
What are the biggest quick wins?
Almost always: (1) hunt standby power — 30–100 W always-on totals 260–870 kWh/year; (2) switch remaining halogen or incandescent lights to LEDs — 80–90% saving on lighting; (3) drop wash temperature from 60 °C to 30–40 °C — cuts washing energy by ~60%; (4) unplug or eject old fridges/freezers from the garage — 300–600 kWh/year each. The audit above surfaces the highest-consumption lines automatically.
How much can I realistically cut without buying new appliances?
Behaviour changes alone typically save 5–15% of an average home bill. Adding smart plugs to eliminate standby, tuning thermostat setpoints and shifting laundry to off-peak tariff hours push this to 15–25%. Larger cuts (30%+) require capital investment: insulation, LED replacement of remaining halogens, heat pump replacement of resistive heating, or A+++-rated white goods.
Does using more sustainable electricity change anything?
Buying a "green tariff" typically does not add new renewables to the grid — the CO₂ number in this calculator reflects your actual grid mix. Real reductions come from consuming less, shifting consumption into cleaner hours (usually daylight or windy nights), or self-generating with rooftop solar. See the Solar Payback Calculator for the numbers on the last option.

Keep exploring

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Home Energy hub

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Smart-home savings guide

The behaviour and hardware changes with the shortest payback.

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Heat Pump Savings

If heating is your biggest line, a heat pump usually wins.

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Solar Payback

Cover a chunk of your consumption with rooftop PV.

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EV Charging Cost

If you drive an EV, add its kWh to the audit above.

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Carbon hub

Put the CO₂ side of your audit in context of the full footprint.